2 Tips for Common Denominators
Monday February 26, 2007
When young learners start to work with fractions, they often struggle to find the common denominators. There are a couple of methods that work every time and with a little focus on each method, common denominators will no longer be the problem. Remember, the denominator is the bottom number in a fraction or what the whole represents.
Comments
Finding a least common denominator is one of the most difficult skills for students to master; especially students who are not comfortable with their multiplication facts.
Method 2 of having students find the Least Common Multiple worked best for me in helping students find the LCD.
Method 1 sometimes creates a common denominator that needs to be simplified.
For example under Method 1, the common denominator for 1/6 + 2/9 would be 54. This is much larger than the LCD of 18 using the common multiple method.
Method 2 also makes the multiplication easier when renaming each fraction in terms of the LCD.
This is a very nice site. Keep up the good work.
I taught for 22 years in Middle School and 6 years in High School.
You are so right dave. Kids must be good at multiplication and reducing.
Method 1 was my favorite, especially in comparing fractions and ordering them in least to greatest order, etc. If you’re not asked to simply, Method 1 is the easiest and quickest way to compare fractions. If you go with Method 2, you will run into a time-consuming problem and may end up with an even bigger problem when you come across denominators such as 11, 9, and 5, taking a longer time to get the least common multiple.